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New Member New member Intro - SRX 250 - 2 stroke?

Discussion in 'New Members Say Gday' started by Nosaki Faki, Apr 4, 2021.

  1. Nosaki Faki

    Nosaki Faki Member

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    G'day I found my way here looking for SRX250 info. There is more useful stuff here than anywhere else I have found so it was a no brainer to sign up.
    I picked up a rough non runner a few weeks back for a couple hundred dollars.
    Realising it will be a long road to restore it I have decided to go the Mod route.
    I should probably start a build thread like others have done and will get to that once introductions are done.
    Spent a few days on it now swapping FZR250 3ln1 front and rear ends onto it, which gave me a few little challenges, rear brakes are the worst of it so far, but I'm happy with the progress so far.

    Here is where i might get a bit controversial.
    I have access to a cheap RD 250 motor, I like the idea of trying to put it in the SRX.
    Has anyone else ever tried something similar or am I a bit insane?


    SRX.1.jpg SRX.2.jpg SRX.4.jpg SRX.5.jpg SRX.8.jpg SRX.10.jpg
     
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    Last edited by a moderator: Apr 4, 2021
  2. Andych

    Andych Senior Member Premium Member

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    Yamaha did do almost a 2 stroke version of the SRX... The RZ250R frame is very very similar to the SRX..
    With the FZR front and rear end conversion it is fairly straight forward other than trying to sort out rear brake master cylinder mounting and actuation..
    I have done it on my SRX but I have used the Japan only SRX3WP swing arm and brake etc..
    The other area to watch our for is the chain... On an SRX when you get to near to full droop on the rear suspension the chain will contact the swing arm... it has caused some people a few issues. The 3WP swing arm is similar to the standard drum brake item so no problems with fouling from the chain.
    The only other thing to check is that it will be able to be registered. Mods may be just too out there without an Engineers certificate.
    https://www.motorcyclespecs.co.za/model/yamaha/yamaha_rd250 82.htm
     
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  3. Nosaki Faki

    Nosaki Faki Member

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    I have had a good read through your build thread, you do very nice work.

    As you say the front end was easy, rear was fairly straight forward as well really, I had to make a few bushes and spacers to
    be able to fit the FZR shock and I will have to visit a mate with a lathe to machine the inner race of the needle roller in the knuckle to accept the bolt from the SRX. The only place I could find to mount the brake master is using one of the 3 holes in the frame below the side cover, still need to make a bracket to secure the top bolt, and had to make a Z shaped bracket to offset the rod from the master to the pedal. I'm pretty sure it will stop me putting the airbox back in so I will have to figure out what I'm going to do there. If I do the engine swap I will likely go foam filters on a bit of a runner. If I use the standard engine I will have to either mod it or make a custom box.

    Thanks for the tip on the chain, I will look into that tomorrow when I get back into it. maybe I could introduce an idler/ tensioner.
    Gauges will be another interesting thing as well since the FZR top clamp makes mounting the original's near impossible.
    I have also thought about an engine swap from something like a ZZR so I won't get too far ahead of myself on the gauges until I work out what motor to use.
     
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  4. edwardo

    edwardo Well-Known Member Contributing Member

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    Love your work!

    Kinda a hijack, I have 3ln forks and triples sitting my shed, bought for a conversion at some point. Are tapered roller bearings in the right sizes readily available? Did the forks just slot in?

    I need rotors and calipers etc too.

    I have a fzr250 rear wheel and also a 3wp caliper bracket, I am hoping it can all slot together while retaining the 51y swing arm. Probably will have trouble mounting the mc /sigh
     
  5. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    An rd250 engine into an srx frame would be fun, the biggest challenge is rubber mounting the engine so it doesn’t shake itself to pieces.

    Power to weight will be great as the srx250 only weights 123 kegs in standard form
     
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  6. Nosaki Faki

    Nosaki Faki Member

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    Yes tapered bearing kits are available, Wemoto list them as the same for both models, just need to knock the races out of the head tube. I re used the existing ones from the FZR.

    I'm not sure the 51y swingarm will be wide enough for the FZR wheel or the axle could be different from memory when I was researching parts. Andych went through all that process, I reckon if it was going to work he would know.
     
  7. Nosaki Faki

    Nosaki Faki Member

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    I will pick up the engine either way since it is stupid cheap and see if I can make it work. Hopefully I can work something out.
    Otherwise I will have to look more closely at a twin or talking another mate out of his tt350 top end.
    I'm up for the challenge, just play a bit of Suck it and see!
     
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  8. gregt

    gregt Well-Known Member Premium Member

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    FWIW, there's a guy here in NZ racing an FZR250 rolling chassis - with a worked RZ350 engine fitted.
    Goes well.looks good. Seemed to be an easy build.
     
  9. Andych

    Andych Senior Member Premium Member

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    Agree that the front steering bearings are the same so the front end goes on no trouble, other than the lock stop position needs to be changed but it isn’t a big issue.
    They FZR250 3LN rear wheel works in the SRX swing arm but you will need to modify the swing arm a lot for the rear brake.
    It is far easier to buy a 2nd hand swing arm and pivots etc from Japan through Jauce or the like. It is just less hassle and then the FZR shock works as the bottom Clevis is the same and you can buy the correct size sleeve for the top bolt new from Yamaha.
    As an aside, you can’t use the FZR rear shock with the standard SRX swingarm.
    If anyone needs front forks, discs or calipers for their conversion then let me know. I am sure I can help



    Sent from my iPhone using Tapatalk Pro
     
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  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Do it, should be great. Just watch Project Binky and then you will believe you can do anything.
     
  11. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    Blinky ftw
     

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